What does the term "network topology" mean?

Network topology is the way network devices (nodes) and the connections between them are organized and arranged. Put simply:

Network topology describes how devices are connected and along which paths data travels through the network.

This is one of the basic networking terms, and it shows the structure, the logic of connections, and the characteristics of data transmission.

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#Why is topology needed?

Topology lets you understand:

• how devices are physically connected
• how data exchange is organized
• where bottlenecks are possible
• how the network will behave during failures
• how to scale it

Administrators use topologies for:

• designing a new network,
• troubleshooting,
• assessing load,
• choosing optimal equipment.

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#Types of network topology

#1. Physical topology

Describes how cables are actually laid and how equipment is arranged.

Example: cables from all PCs go to a single switch → a physical "star".

#2. Logical topology

Describes how traffic is actually transmitted between devices, even if the physical structure is different.

Example: In Ethernet the physical topology is a "star", but logically devices operate on a "shared bus" (broadcast domain).

Important: Interviews often ask about the difference between the two.

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#Main topology types (classic)

#1. "Bus" topology

All devices are connected to a single shared channel. Historical (Ethernet 10BASE2/5), now almost never used.

Pros: simple, cheap. Cons: one cable damage breaks the whole network; collisions.

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#2. "Star" topology - the most common today

All devices connect to a central device (a switch).

Pros:

• a failure of one PC does not affect the others
• easy to expand
• high performance

Cons: a switch failure → the network becomes unavailable.

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#3. "Ring" topology

Devices are connected in a circle.

Used in Token Ring, FDDI. Now almost never applied.

Pros: no collisions. Cons: a break in the ring = problems.

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#4. "Mesh" topology

Each device is connected to many others.

Full mesh - when every device connects to every other. Partial mesh - when only critical nodes have multiple connections.

Pros:

• high fault tolerance
• excellent bandwidth

Cons: expensive and hard to scale.

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#5. "Tree" topology

A hierarchy of switches: root → distribution → access.

This is the basis of modern corporate LANs.

Pros:

• scalability
• structure

Cons:

• dependency on the upper levels of the tree

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#Examples of topologies in real life

• Home network - usually a "star": all devices → a home router.
• Offices - a tree topology with multiple switches.
• Data centers - Clos/Fat-Tree (variations of tree and mesh).
• Wireless mesh networks - Wi-Fi Mesh at home or in large venues.

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#How to answer in an interview (short and clear)

Network topology is the way connections between devices are organized and the path traffic takes. Physical and logical topology are distinguished. Main types: bus, star, ring, tree, and mesh. In practice, the star topology and tree structures are used most often.

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#Cheat sheet

• Topology = network structure: how devices are connected.
• There is a physical and a logical one.
• Types: bus, star, ring, mesh, tree.
• In a modern LAN, mostly star and tree/Clos.